At the height of his political celebrity, Gov. Chris Christie of New Jersey persuaded dozens of Democratic officeholders to back his 2013 re-election campaign. The implied transaction seemed simple: Support a well-liked Republican and win a measure of good will from him, perhaps even some acclaim by association.

One such attempted deal went notoriously wrong in Fort Lee, leading to the indictment on Friday of two former Christie appointees, and a guilty plea by another former associate.

Now, as Mr. Christie fights for his political future, it is New Jersey Republicans weighing how closely to associate with a governor whose popularity has faded in the polls. The issue is not some distant abstraction: The state’s entire General Assembly is up for election this year, and the next governor’s race looms in 2017.

Mr. Christie’s support is no longer an unalloyed asset to Republicans. State Senator Michael Doherty, a conservative lawmaker who has been critical of the governor, said the recent scandal would clearly affect the party in upcoming elections.

“It’s going to be relevant to the reputation of the statewide Republican Party, and whether a Republican’s going to have a shot of being elected governor in 2017,” Mr. Doherty said.

Not so long ago, Republicans hoped that Mr. Christie’s electoral victories would provide a durable boost to the party. After nearly a decade out of power, Republicans were offered a toehold in Trenton and help competing in difficult areas of the state, including populous northern New Jersey.

Yet over the last year, some of the governor’s signature political trophies have been stripped away. A landmark pension-reform deal was struck down in court, denting Mr. Christie’s image as a problem solver.

Mr. Christie, who was first elected thanks in part to his profile as a clean-cut prosecutor, is now stuck parsing legalisms in an effort to play down his administration’s culpability in the events that led to the federal indictments last week.

The aide and appointees were accused of a conspiracy in shutting several lanes of traffic approaching the George Washington Bridge to punish the mayor of Fort Lee for his failure to endorse the governor’s re-election.

Mr. Christie, who is considering a run for president, has denied any wrongdoing and disavowed any knowledge of the retribution scheme. Paul J. Fishman, the United States attorney for New Jersey who announced the indictments, said there were no plans to charge anyone else in connection with the bridge inquiry based on the evidence gathered so far.

The governor is still expected to play an important role in the legislative elections this year, as the party’s most visible figure and its most formidable fund-raiser.

Jack M. Ciattarelli, a Republican member of the Assembly, called the indictments “infuriating and sickening.” He said he would take Mr. Christie at his word that he was not involved in the lane closings, but criticized the governor’s selection of associates. “People who work in his administration seem to have been intoxicated with his popularity, or their power, and they abused it,” he said.

Mr. Ciattarelli, who is viewed as a possible statewide candidate, added that Republicans would be wise to prepare for life after a Christie administration, likening the governor to a pair of presidents who largely defined their parties.

“Every party needs to move on and out from under the shadow of as dominant a figure as Kennedy was, as Reagan was, and here in New Jersey, as Christie is,” he said.

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Mr. Christie on election night in Atlantic City in 2013.CreditRichard Perry/The New York Times

Even a gentle inching away from Mr. Christie would represent a significant departure for New Jersey Republicans, who have tied their fortunes to the governor’s, for better or worse, since his election in 2009.

Most New Jersey Republicans have remained publicly supportive of the governor throughout the ordeal of the long investigation. But there have been scattered signs that Mr. Christie’s once-firm grip on the state Republican establishment may have slipped along with his approval ratings.

As Mr. Christie has publicly entertained the notion of a run for the presidency, several prominent New Jersey Republicans once aligned with the governor have instead supported Jeb Bush, the former governor of Florida. Among them are Woody Johnson, the owner of the Jets, and State Senator Joe Kyrillos, the party’s 2012 nominee for the United States Senate.

Mr. Kyrillos, once one of Mr. Christie’s most enthusiastic supporters, also broke with convention when he publicly rebuked the governor last winter for mismanagement at the Port Authority of New York and New Jersey.

Despite periods of intense personal popularity, Mr. Christie has had only limited success at lifting the prospects of other Republicans. In 2013, the party made a major push to win control of the State Senate, hoping to ride Mr. Christie’s political coattails as he romped to re-election. Though he won a second term by more than 20 percentage points, Republicans failed to pick up a single seat in the chamber.

Still, the sheer breadth of Mr. Christie’s victories appeared to hold out the possibility of a larger political shift. In 2009, he won his first election by a wider margin than any Republican since Thomas H. Kean’s landslide re-election a quarter-century earlier.

National Republicans, reeling after their defeat in the 2012 elections, looked to Mr. Christie as a model for expanding the party’s electoral reach. Indeed, in his re-election campaign, Mr. Christie did the seemingly impossible, for a Republican: He won a clear majority of female and Hispanic voters, and split the youth vote almost evenly with his Democratic challenger, Barbara Buono, a state senator.

In his victory speech, Mr. Christie embraced the role, urging his fellow Republicans to campaign “in the places where we’re uncomfortable,” to court voters traditionally wary of conservative candidates.

Republicans, including Mr. Christie’s admirers, now say that the hope for a lasting realignment in their favor has waned. In places, the party’s gains have already been reversed: In last year’s elections, amid a national Republican landslide, voters ejected a Republican county executive, Kathleen A. Donovan, from the top post in Bergen County, the ultra-diverse population anchor of northern New Jersey.

Ms. Donovan, who had first won the job in 2010, a year after Mr. Christie’s first election as governor, said he had supported her energetically in her second, unsuccessful campaign. But other forces were decisive in the race, Ms. Donovan said.

“The demographics continue to change and trend toward Democrats,” she explained. “The governor has done the very best job he could, in terms of helping Republicans overcome Democrat numbers, but there are structural problems in New Jersey.”

The Democrats are not without their own challenges, having done little to fix the woes that allowed Mr. Christie to win office in the first place: high state and local taxes, a budget deep in the red and a lingering perception of ethical lapses after a long string of corruption cases. (Many were prosecuted by Mr. Christie, in his days as a United States attorney.)

Jon M. Bramnick, the Republican leader in the State Assembly and a potential candidate for governor, said the party planned to put Democrats on the defensive by focusing on their long record of tax increases. The main issue in this year’s legislative election, he said, would be making New Jersey an affordable place to live, and the Democrats’ record of doing the opposite.

Mr. Christie has agreed to play an active role in this year’s campaign for control of the legislative chamber, Mr. Bramnick said. “I think the overwhelming theme is not going to be Chris Christie,” Mr. Bramnick said. “I think the overwhelming theme is: Do you send back the same team that’s been there more than a decade?”

Representative Bill Pascrell, a Democrat who represents Fort Lee in Congress, cautioned Democrats not to grow overconfident about Mr. Christie’s downfall. After all, he noted, many of the party’s officeholders endorsed the governor for re-election and cooperated with his agenda in Trenton.

“There’s a lot of baggage out there on everybody’s shoulders,” Mr. Pascrell said. “Neither party is privy to virtue in New Jersey.”

A version of this article appears in print on , on Page A18 of the New York edition with the headline: Christie’s Grip on State G.O.P. Politics Shows Signs of Slipping Amid Scandal. Order Reprints | Today’s Paper | Subscribe